(11-19-2014 03:16 AM)Brad Barton Wrote: Did I read somewhere that the ACT from the HP-25 was a suitable replacement for the ACT in the HP-97? I have no clue about the various architectures, so this could be a dumb question, but will one of these work in the HP-97?

No, it's not a dumb question. One of these could work in the near future, but there is some work to do.

I tried the new ACT on my HP-97 today. It did not yet execute the original ROM Code, but electrically it works. The display digit order is reversed, compared with HP-25 and has 15-digits, the digits must be sendt sequentially right to left to the display driver chip. After adapting the firmware, I have now complete control over the display.

Also the original ROM Code can be read. Keyboard and switches don't work yet. The Print switch has three positions and is multiplexed with the Prgm/Run switch. It must be figured out, how to read them.

I admit, that printing and Card reading will still need a lot of research. I don't know when this will be done. But using the new ACT in HP-97 for arithmetik and programming should be not too far away.

At least it fits! See pictures below.

Unfortunately the segment driver is different, it doesn't code the letter 'P' any more, it is replaced by letter C for displaying 'Crd' , so it is not possible to display 'HP-97'. I choose HC-97 instead, that means 'Hp Calculator-97'

I have an HP-25 on which the RAM doesn't work at all - no program steps, no memory registers. Would this machine be a suitable candidate? I understand that the ACT chip and the RAM are separate, but perhaps your ACT replacement does not use the original RAM.

I also have an HP-25C which works fine for a while and then gradually starts to forget things as it warms up. Does your replacement ACT work in an HP-25C, and does it replace enough of the internal circuitry to make a fix a possibility?

I have an HP-25 on which the RAM doesn't work at all - no program steps, no memory registers. Would this machine be a suitable candidate? I understand that the ACT chip and the RAM are separate, but perhaps your ACT replacement does not use the original RAM.

Yes.

I could channel a certain frequent poster and suggest you RTFT. ;-)

From the top post:

(11-17-2014 03:40 PM)PANAMATIK Wrote: To avoid questions:
The chip is suitable only for HP-21, HP25 etc. devices with PMOS design, not for Continuous Memory CMOS devices.
It executes either the original ROM Code from the on board ROM Chips or internal ROM Code.
It contains a program interface for updating the firmware or for other purposes.The RAM Chip is not longer needed after the replacement, because the chip does have enough internal RAM.

I have an HP-25 on which the RAM doesn't work at all - no program steps, no memory registers. Would this machine be a suitable candidate? I understand that the ACT chip and the RAM are separate, but perhaps your ACT replacement does not use the original RAM.

Yes.

I could channel a certain frequent poster and suggest you RTFT. ;-)

From the top post:

(11-17-2014 03:40 PM)PANAMATIK Wrote: To avoid questions:
The chip is suitable only for HP-21, HP25 etc. devices with PMOS design, not for Continuous Memory CMOS devices.
It executes either the original ROM Code from the on board ROM Chips or internal ROM Code.
It contains a program interface for updating the firmware or for other purposes.The RAM Chip is not longer needed after the replacement, because the chip does have enough internal RAM.

Thank you! Not sure how I missed that. I think the question about HP25C support is still open, though.

(12-29-2014 12:08 AM)Nigel (UK) Wrote: I think the question about HP25C support is still open, though.

Nigel (UK)

I bought two HP-25C in the last weeks, one working, one not working for testing. The latter isn't delivered yet. I didn't want to replace the ACT in the first, but measured the signals and it will be 99% sure that the circuit works.

(12-29-2014 12:08 AM)Nigel (UK) Wrote: I have an HP-25 on which the RAM doesn't work at all - no program steps, no memory registers. Would this machine be a suitable candidate? I understand that the ACT chip and the RAM are separate, but perhaps your ACT replacement does not use the original RAM.

Yes, as Mark posted you before, I confirm that the original RAM is not longer used. And since I had some days after XMAS for programming, it will have two RAM banks now, which gives you 8 additional registers and 49 additional program steps, which can be swapped by f ENTER. And both are Continuous Memory.

I wanted an FPGA solution first, because this would give a very accurate timing, but I didn't find a suitable chip. For the size of logic, needed to implement all the ACT arithmetics, the chips would have hundreds of IO pins, which did not fit into the limited area of the ACT socket. Obviously there is no market for FPGAs with 10000 gates with only 20 pins. Another reason was PMOS logic levels. Common FPGAs would have needed much more level converters.

I used a midrange PIC16F controller instead and could have used ARM controllers as well.

I used a midrange PIC16F controller instead and could have used ARM controllers as well.
Bernhard

Thanks! My bet was an LPC111x but a 5Volt 16F might be a better choice when handling such weird signal levels..
I still wonder how the guys where able to put all the stuff inside such limited hw space at that time. 2k words of rom for all the hp25 stuff.. I am an owner, but ACT works fine. I did the zener mod so it seems my ACT is safe for now
Nice job, congratulation!
P.

I think if all goes well, the first ACTs will be ready to ship within this month, as indicated earlier.

Meanwhile I was working very hard on the software part. I build two versions of the ACT. The standard version just does what an ACT should do: emulating the original HP-25 or HP-21 and nothing else. The extended version for HP-25 only has a built in ROM library for programs. It gives space for 100 programs of up to 49 steps, an equivalent of 100 magnetic cards, if the HP-25 would have had a card reader. I included all 54 programs of the original HP-25 Program Collection. But there are still 46 programs left. I will contribute one program by myself, thus I need more 45 programs from you.

Would you like to make proposals for HP-25 programs, that you think anybody would like to have, or those that are well known, but I don't know them, that can be included into the ACT. In other words: What are the best HP-25 programs ever?

The key Sequence to load a program from the library will be f RCL . 00-99

I need just a normal listing of a maximum of 49 steps and a description how to use it. I would carefully type it in manually and make it a fixed part of the extended ACT chip. The description should be similar to the HP-25 program collection and I could make it part of the ACT manual. I don't know how to deal with copyrights. Your proposals should be free from any copyrights, otherwise I cannot use them.

(12-29-2014 12:08 AM)Nigel (UK) Wrote: Thank you! Not sure how I missed that. I think the question about HP25C support is still open, though.

Nigel (UK)

Hi Nigel,

I hope this is good news for you,

the question about HP25C is settled: supported!

The defective HP-25C, that I bought some weeks ago, was kept by customs until today. I got it from serbia. It was in a terrible condition, but unexpectedly after cleaning contacts and sticking everything together: it started up and worked!

Now I had the unloved duty to remove a working ACT from a HP-25C. I don't know how often that happens? But it went well and either the original ACT and the new ACT could be placed into the ultra low profile socket and both are working.

Is the 29C supported as well? I've got one with a defective ACT (I guess) - received it in this state from a seller on TAS. Would be nice to be able to repair and upgrade it "in einem Aufwasch".

d:-)

Hello Walter,

I don't know, because i don't have a HP-29C, I assume it will not work "auf Anhieb". But what you can do is replacing an ACT of some good HP-25 with my extended HP-25 version and place the original ACT in your HP29C, this will get you a working HP29C and an ultra HP-25C.

(12-29-2014 12:08 AM)Nigel (UK) Wrote: Thank you! Not sure how I missed that. I think the question about HP25C support is still open, though.

Nigel (UK)

Hi Nigel,

I hope this is good news for you,

the question about HP25C is settled: supported!

The defective HP-25C, that I bought some weeks ago, was kept by customs until today. I got it from serbia. It was in a terrible condition, but unexpectedly after cleaning contacts and sticking everything together: it started up and worked!

Now I had the unloved duty to remove a working ACT from a HP-25C. I don't know how often that happens? But it went well and either the original ACT and the new ACT could be placed into the ultra low profile socket and both are working.

This is the first HP-25C with 5439 program steps "Continuous Memory".

Bernhard

Wonderful! I love the look and feel of the HP-25; it will be fantastic to have one (or two!) working reliably.

By the way, would your ACT replacement be damaged by a charger connected without batteries in place?

(01-07-2015 09:09 AM)Nigel (UK) Wrote: By the way, would your ACT replacement be damaged by a charger connected without batteries in place?

Nigel (UK)

I dont want to try in situ, because RAM ROM chips are still in danger. I think especially the RAM chip is sensible for damage too. The ACT controller itself is protected by a resistor at the Power Pin. I think it will survive, but others will probably not.

But if it happens though, there will be a replacement available any time.

By the way, I finished the ACT software today and will go on with the manual now. There are a few new features included.

Is the 29C supported as well? I've got one with a defective ACT (I guess)
Would be nice to be able to repair ... it "..."

I acquired a defective HP-29C yesterday, not yet delivered. But now we have the same goal. I think it will not be defective for ever!

Also a HP-22 will arrive tomorrow, and HP-27 next week. Thus I got the complete woodstock set. And my intention is not to put them in a showcase. At the moment I have already two working original ACTs without having any use for them.